One of the pitfalls in Unified Communications (UC), real-time applications, streaming media, or online video gaming, is Network Jitter.
Jitter is a delay variation that puts stress on the receiving endpoint, as it is trying to figure out the right sequence of data packets. This negative aspect leads to congestion and packet loss.
There is no network free of jitter.
But some networks have it close to zero. By knowing about the jitter in your network and keeping track of it, you can reduce it. The idea to stay on top of network jitter is to optimize the user experience and have smooth communications.
Lets go over what is Network Jitter and How to Monitor it. Lets get deep into the concept, how to calculate it, and provide some of the Best Jitter Monitoring tools and software.
- What is Network Jitter?
- Network Jitter Example
- How can Network Jitter be calculated?
- How can Network Jitter be Monitored?
What is Network Jitter?
Jitter is another word for inconsistency. It refers to the fluctuation in the latency of the packets flowing through the network.
In other words, it is a variance in delay between packets sent over the network, usually measured in milliseconds (ms). Network jitter happens due to network congestion, interference, route changes, etc.
What does Network Jitter affect?
Jitter is a negative aspect of the network. It affects latency-sensitive applications and hurts the user experience. Jitter introduces inconsistencies which influence the quality of communication and data transfer speeds. It affects any real-time communication, particularly UC such as video conferencing and VoIP calls, streaming media, online video gaming, Desktop-as-a-Service using VDI, etc.
Network Jitter Example
In a perfect world, jitter should be zero. On a network without jitter, every single packet would arrive with the ideal sequence and with the same delay, 10ms for example.
Let’s say that “Computer X” is sending packets over to “Computer Y” without jitter. These packets will be transmitted at equal intervals, and the receiving computer will be able to process them seamlessly.
In a network affected with jitter, these intervals are inconsistent. The total transit time of each packet would be disrupted. For example, the first packet could arrive with a 20ms delay, the second with a 60ms delay, the third one with a 10ms delay, and so on. Network Jitter refers to this fluctuation in latency.
How can Network Jitter be calculated?
Finding network jitter can be as easy as having a bad experience. It can be felt when the communication feels skimpy, the voice on an IP-phone call would sound robotic, or an online video game would lag all the time.
To find out the network jitter, pull out the “Command Line” or “Terminal” and throw a ping to any destination. In the example below, a PING was sent to the Gateway: 192.168.0.1. In the example below, there are 24 PING packets inconsistent in delay.
The jitter is found by finding the average of the time difference between each packet sequence.
The difference between 58ms and 1ms: 57 ms.
The difference between 1ms and 58ms: 57 ms.
The difference between 1ms and 1ms: 0ms.
The difference between 37ms and 1ms: 36ms. And so on…
We found a total of 16 values (excluding seven 0ms) with an average of 41. 660 (the total difference) / 16 ≈ 41.
So the network jitter of our test is 41 ms.
Network Jitter Calculator
Now, you know the theory behind how network jitter is calculated. But doing these calculations, every time can be tiresome.
There are some online network jitter calculators like 3rdEchelon’s, that can help you with this process. Just perform a ping test, visit their website, and paste the ping results on the box. The application will give you a calculated jitter based on the extracted delay times.
How can Network Jitter be Monitored?
Nobody is safe from network jitter. Fortunately, some tools can measure and display information about jitter and other negative aspects of the network. Some of them will even create alarms and reports.
1. SolarWinds VoIP & Network Quality Manager
High network jitter is one of the worst causes of the bad quality in VoIP calls. SolarWinds offers the VoIP & Network Quality Manager (VNQM) which is capable of monitoring network jitter and latency so that you can maintain good call quality. The VNQM can calculate the jitter and latency right from the packet stream.
With this software, you’ll be able to keep track of VoIP calls and Call Detail Records (CDRs), and measure the performance metrics (jitter, latency, packet loss, and MOS) and monitor the quality of the VoIP traffic. With SolarWinds VNQM, you can search and filter VoIP calls based on their jitter measurements.
The SolarWinds VNQM can do more than monitoring network jitter. It can also:
- Monitors VoIP call QoS Metrics (Jitter, latency, packet loss, and MOS)
- Advanced troubleshooting for VoIP calls performance.
- Keep tracks of WAN using Cisco IP-SLA.
- It creates a visual call path trace.
VNQM comes in four different licenses, the SLA5 ($1,530USD or €1,380), the SLA25 ($4,830USD or €4,355), the SLA50 ($7,317USD or €6,595), and the SLAX ($12,287USD or €11,075). You can also get a quote from their official site.
a free 30-days trial, fully functional VoIP & Network Quality Manager from SolarWinds and measure network jitter on all your VoIP calls.
2. Paessler PRTG
PRTG Network Monitor is another monitoring tool that can detect jitter and monitor it continuously. This software employs sensors to monitor separate elements within a device. With these sensors, you can watch a single component or metric such as CPU utilization, free disk space, bandwidth, traffic, delay, jitter, etc.
A single device can have one or up to a thousand sensors monitoring different aspects.
PRTG Network Monitor comes with four different sensors to help you keep track of network jitter:
- QoS Round Trip Sensor:
This sensor monitors the quality of the connection. It measures and displays network jitter (in ms), packet loss, latency, and MOS.
- QoS One Way Sensor:
- This sensor keeps track of the quality of the connection between two PRTG probes. It measures and displays jitter, loss, latency, and MOS.
- Cisco IP SLA Sensor:
This sensor uses SNMP to monitor Cisco IP SLA. It also measures and displays jitter.
- Ping Jitter Sensor:
This is a sensor only for jitter. It uses a series of pings to measure and calculate jitter.
The following screenshot shows the Sensor Cisco IP SLA showing Jitter, latency, RTT, MOS, etc.
The price for a license of PRTG Network Monitor depends on the number of sensors that you’ll monitor. The most basic license PRTG 500 starts at $1,330 (or €1200) which allows monitoring up to 500 sensors and one server installation.
PRTG100 for free for unlimited time and start monitoring your network jitter today! You can also apply for a fully functional free trial if you want to keep track of more than 100 sensors.
3. StarTrinity Continous Speed Test Tool
StarTrinity’ Continuous Speed Test Tool is a free and open-source jitter and packet loss test tool. It is capable of measuring the quality of your network connections by sending multiple bidirectional UDP connections to different servers. The software records the timestamps into the packets and obtains jitter and packet loss. Once is finishes the test, it will display the following results:
- Upload and download bandwidth
- Upload and download jitter
- Upload and download packet loss
- Delay in RTT.
- Uptime percentage and downtime history.
The Continuous Speed Test Tool is supported by Windows, Android, and Linux. You can also run the HTML version, which allows online speed tests from your browser.
Price: Free and open-source.
Download the Continuous Speed Test Tool from StarTrinity’s site.
4. MegaPath’s Speed Test Plus
MegaPath’s Speed Test Plus is an HTML5 free online test for bandwidth. It keeps track of your Internet speed and quality. But it does not only give you download and upload speed as most online speed tests do, but it also shows you, jitter and latency.
When you do a test, select a target server (or City) to send ping packets. The tool does not work with ICMP ping packets; it sends HTTP requests to the target server and measures the response time. It then displays:
- Download bandwidth in Mbps
- Upload bandwidth in Mbps
- Latency in ms
- Jitter in ms.
The Speed Test Plus is an online free tool.
You can run the tool from your browser. The software is not downloadable.
Jitter is a negative metric on your network that should be avoided at all costs. It hurts all real-time communications, your VoIP, videoconferencing, online gaming, and makes your critical applications, unreliable.
Although there is not a perfect world, free of jitter, you can stay on top of it and reduce it. If you want to know your network jitter values at the moment, a ping test and a calculator can do the trick. But if you're going to keep track of it continuously, a jitter monitoring tool will be your best friend.
All the tools showed above can monitor jitter in some way. There are special tools like SolarWinds VNQM, that can keep an eye on it, specifically for business-critical applications like VoIP calls, and give you reports. And there are also comprehensive monitoring tools like PRTG, that can keep track of your jitter in Cisco IP SLA, VoIP.
If you are feeling jitter in your network, start a free trial today from one of the tools above, and stay on top of it.